The goal of this study was to assess how brain markers associated with age-related changes in cognition influence the rate at which cognitively normal individuals (CDR=0) progress to mild functional impairment as indicated by a Clinical Dementia Rating of 0.5. Participants included 259 clinically normal older adults (M=73.4 years old) from the Harvard Aging Brain Study with at least one follow-up neuropsychological assessment and all imaging measures at baseline. Participants were assessed at baseline for magnetic resonance imaging markers of brain volume and thickness, white matter lesions and diffusion characteristics, and resting state functional connectivity in multiple networks; positron emission tomography markers of glucose metabolism and amyloid burden; and cognitive factor scores of episodic memory, executive function, and processing speed performance and change over time in these cognitive scores. Cox regression models were used to assess the time to progression to CDR of 0.5 as predicted by baseline brain markers and cognition, covarying for age, sex and education. Sixty-four participants (24.7%) progressed to a CDR of 0.5 over an average follow-up of 3.73 years (range: 1-6 years). Low hippocampal volume, decreased functional connectivity of the default mode and salience networks, high amyloid burden, and lower memory performance all significantly contributed to the rate of progression while controlling for contributions of other biomarkers, cognitive measures, and covariates. These results indicate that brain markers independently influence the rate of progression on the CDR global score over and above the predictive value of baseline or change in cognitive performance.